What does one mean by exothermic and endothermic reactions ? Give examples.

Explanation

A chemical reaction where the energy required for bond breakage is less than the energy required for bond formation, resulting in release of energy during the reaction is known as an exothermic reaction.
e.g. : `CaO+H_(2)OtoCa(OH)_(2)+"energy"`.
A chemical reaction in which the energy required for new bonds formation is less than the energy required for bond breaking, resulting in consumption of energy during the reaction is known as an endothermic reaction.
e.g. : `ZnCO_(3)(s)overset(Delta)(to)ZnO(s)+CO_(2)(g)`.